Primum Non Nocere
by TotallyUtterlySherlocked
Summary: "First do no harm." That had been the basis for an entire lesson in John's university bioethics class. It was something he'd always remembered. He kept it in mind, always, on the battlefield, and in his own locum work. Now, when he's living out his own medical nightmare, he must force Sherlock to break one of the principles of medicine he'd spent his entire life protecting.


**A/N: I'm the worst person in existence, OK? I'm just establishing that immediately so there are no questions about my motives by the end of this story.**

**DISCLAIMER: I own nothing. Please don't sue me.**

* * *

It was an ordinary day on Baker Street, and even more ordinary inside 221B.

Of course, in 221B, _ordinary_ was a very relative term.

Ordinary in this case meant John waking up with a start due to a deafening bang from the kitchen downstairs. He glanced at the clock and groaned. It was 5 AM. It was his day off. And the bloody headache he'd had when he went to bed hadn't gone away.

When he'd managed to push himself out of bed and down the stairs, the pounding behind his eyes was enough to make him wince. He made a conscious effort to maintain a neutral, if slightly annoyed, expression when he'd gotten to the kitchen, where Sherlock seemed to be deep in an experiment involving...kidneys, and something that looked highly acidic.

"What was that bang?" He asked, now unsure if he really _wanted_ to know.

"Hmm?" Sherlock didn't even bother to look at him.

"I said," John stopped, gritted his teeth against a wave of pain, and then continued. "What was that bang?"

The detective looked up, studied John, then looked down. "You ought to get those headaches checked out," he said distractedly.

"Sherlock," John's tone was bordering on edgy.

Huffing, Sherlock stared at him. "I might've lit a tea bag on fire and attempted to extinguish it with acid." He said, clearly annoyed at having to explain himself.

Ordinarily John would've been furious, but honestly, he was in too much pain, too exhausted, and...too...dizzy?

He opened his mouth to say something else, probably to tell Sherlock he was going to faint, but he was unconscious before he could get a word out.

* * *

He woke slowly, and it took him a few minutes to work out exactly where he was. _Hospital_, his mind told him. The bright light was nearly blinding when he opened his eyes, and he blinked quickly to rid his vision of the colored flashes. He saw Sherlock in a hard plastic visitor's chair next to his bed, fingers flying across the screen of his mobile.

John opened his mouth to ask what the hell had happened, and Sherlock answered before he'd said anything. "You fainted," He looked at John and pocketed his phone in one fluid motion.

"And this necessitated a trip to hospital...why, exactly?" John arched an eyebrow.

Rolling his eyes, Sherlock breathed a heavy sigh through his nose. "Because," he began, already losing his final (thin) shreds of patience. "I couldn't get you to wake up. Nor could Mrs. Hudson, and she was really the impetus behind this," He gestured vaguely around the room. "I was content to let you regain consciousness on your own; your pupils were equal and reactive and you hadn't hit your head on anything hard enough to suggest any sort of brain injury."

John blinked at him stupidly. "Have you been reading my medical textbooks again?"

"No," snapped the detective. "I_'_m not _stupid_, John. I delete things that are unnecessary to my work, and any of those facts could prove vital in establishing a cause of death."

Slowly, John nodded. "Yeah," he said in a distant sounding voice. "You're not stupid at all. That's exactly why you _set a tea bag on fire and tried to extinguish it with acid_." He screwed his eyes up and fixed Sherlock with a glare. Sherlock, to his credit, did his best to look uncomfortable, then broke eye contact.

He was spared one of John's famous lectures by the timely arrival of the on-call doctor. Who looked as though he'd just been plucked from a secondary school graduation ceremony.

Immediately he looked at the chart he held in one hand. "Mr. Watson?" He smiled charismatically, and Sherlock rolled his eyes. "Doctor," he mumbled.

The young man looked at him, confused. "Pardon?"

Huffing a sigh, Sherlock fixed the young doctor with a very patronizing sort of look. "He is Dr. Watson. Not Mr. Watson." He pulled out his mobile and turned away in the chair.

Frowning, John looked apologetically at the red-haired doctor. "Sorry about him," he said kindly.

The man smiled. "No, my apologies Dr. Watson. I'm Dr. Kent. Now," He flipped to another page of John's chart. "Your vitals all look stable, but we did an MRI, CT scan, and a head x-ray when you were brought in just in case. Once those come back, and they look clear, you can go ahead and go home."

John grinned. He _loathed_ hospitals, despite working as a doctor. He'd spent far too much time in them before he came back to England. "Please," he said, extending a hand. "Call me John."

* * *

**A/N: I hope you all enjoy this story; as horribly as it's going to hurt me I'm excited to write it!**

**Please review and...**

**DFTBA darlings, :)**


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